Justify text in R

Question

How do you justify text in R? By justify I mean that each line in a paragraph is exactly the same length (like when you justify in open office or excel). I have tried to find an option with strwrap and cat but have been unsuccessful.

## Get some sample text example from wikipedia api
library(httr)
library(xml2)
name <- "Invictus"
url <- URLencode(sprintf("https://en.wikisource.org/w/api.php?action=parse&prop=text&page=%s&format=json", name))
res <- read_html(content(GET(url))$parse$text[[1]])
string <- iconv(xml_text(xml_find_all(res, "//p"), trim=TRUE), "latin1", "ASCII", sub=" ")[1:2]
(string <- trimws(gsub('\\n|\\s{3,}', ' ', paste(string, collapse=" "))))
# [1] "Out of the night that covers me, Black as the pit from pole to pole, I thank whatever gods may be For my unconquerable soul.  In the fell clutch of circumstance I have not winced nor cried aloud. Under the bludgeonings of chance My head is bloody, but unbow'd.  Beyond this place of wrath and tears Looms but the Horror of the shade, And yet the menace of the years Finds and shall find me unafraid.  It matters not how strait the gate, How charged with punishments the scroll, I am the master of my fate: I am the captain of my soul."

Some attempts using the aforementioned functions

## Using these I can get left/right/center justified text but not
## justified like in other text editing programs or newspapers.
width <- 30
cat(paste(strwrap(string, width=width), collapse='\n'))

## Or with cat
tokens <- strsplit(string, '\\s+')[[1]]               # tokenise to pass to cat
out <- capture.output(cat(tokens, fill=width, sep=" "))  # strings <= width chars
cat(paste(out, collapse='\n'))

Answer 1

Well, if there is no built-in way this works well enough for my purposes. Thanks for the comments above about how to use html styling as well.

justify <- function(string, width=getOption('width'), 
                    fill=c('random', 'right', 'left')) {
    strs <- strwrap(string, width=width)
    paste(fill_spaces(strs, width, match.arg(fill)), collapse="\n")
}

fill_spaces <- function(lines, width, fill) {
    tokens <- strsplit(lines, '\\s+')
    res <- lapply(head(tokens, -1L), function(x) {
        nspace <- length(x)-1L
        extra <- width - sum(nchar(x)) - nspace
        reps <- extra %/% nspace
        extra <- extra %% nspace
        times <- rep.int(if (reps>0) reps+1L else 1L, nspace)
        if (extra > 0) {
            if (fill=='right') times[1:extra] <- times[1:extra]+1L
            else if (fill=='left') 
                times[(nspace-extra+1L):nspace] <- times[(nspace-extra+1L):nspace]+1L
            else times[inds] <- times[(inds <- sample(nspace, extra))]+1L
        }
        spaces <- c('', unlist(lapply(times, formatC, x=' ', digits=NULL)))
        paste(c(rbind(spaces, x)), collapse='')
    })
    c(res, paste(tail(tokens, 1L)[[1]], collapse = ' '))
}

cat(justify(string, width=40))
# Out  of the night  that covers me, Black
# as  the pit from  pole to pole, I  thank
# whatever   gods    may    be   For    my
# unconquerable soul. In  the fell  clutch
# of  circumstance I have  not  winced nor
# cried  aloud. Under the  bludgeonings of
# chance My  head  is bloody, but unbow'd.
# Beyond this  place  of  wrath and  tears
# Looms but  the Horror of the  shade, And
# yet  the menace of the years  Finds  and
# shall  find me unafraid. It  matters not
# how strait  the  gate,  How charged with
# punishments the scroll,  I am the master
# of  my fate:  I  am  the  captain  of my
# soul.

Answer 2

@jenesaisquoi - great solution! But I found it does not work if there is a paragraph break with a space or if strs <- strwrap(string, width=width) returns one or fewer elements.

So, I found an improved version that first splits string by paragraph/line breaks and then applies the same logic:

        justify = function(string, width = getOption('width'), 
                           fill = c('random', 'right', 'left')) {

                        # Split text into paragraphs and remove trailing and leading white space. 
                        paragraphs = gsub("^\\s+|\\s+$", "", 
                        unlist(strsplit(x = string, split = "\n", fixed = TRUE)))

                        # NOTE: Empty elements are paragraphs break. 
                        paragraphs = paragraphs[nchar(paragraphs) > 0] 

                        formatted_text = lapply(paragraphs, function(paragraph){
                                                strs = strwrap(paragraph, width = width)
                                                paste(fill_spaces(strs, width, fill), collapse = "\n")
                                         })

                        paste0(unlist(formatted_text, recursive = FALSE), collapse = "\n")
         }

        fill_spaces = function(lines, width, fill) {

          tokens = strsplit(lines, '\\s+')

          res = lapply(head(tokens, -1L), function(x) {
            nspace = length(x) - 1L
            extra = width - sum(nchar(x)) - nspace
            reps = extra %/% nspace
            extra = extra %% nspace
            times = rep.int(if (reps > 0) reps + 1L else 1L, nspace)
            if (extra > 0) {
              if (fill == 'right') times[1:extra] = times[1:extra] + 1L
              else if (fill == 'left') 
                times[(nspace - extra + 1L):nspace] = times[(nspace - extra + 1L):nspace] + 1L
              else times[inds] = times[(inds <- sample(nspace, extra))] + 1L
            }
            spaces <- c('', unlist(lapply(times, formatC, x = ' ', digits = NULL)))
            paste(c(rbind(spaces, x)), collapse = '')
          })
          c(res, paste(tail(tokens, 1L)[[1]], collapse = ' '))
        }

        nchar_per_line = 50
        string = "Colin\'s practice outfits have reached a new level recently. It's difficult to determine the effect they are having on his teammates - whether they serve more as a distraction or a nice bit of comice releif, but it is clear they fuel Colin's fire and act as a motivator to him. \n\n                                  On another note, Colin's high fives per 36 have been through the roof recently. It really seems like something he's been focusing on in practice lately, as well as putting extra reps in at the gym. \n\n                                  Keep an eye out for Colin, could be an interesting 10 day pickup down the line."
        cat(justify(string, width = nchar_per_line))



    # Colin's practice outfits have reached  a new level
    # recently. It's difficult  to determine the  effect
    # they are  having on his teammates  -  whether they
    # serve  more  as a  distraction  or  a nice bit  of
    # comice releif, but  it  is clear they fuel Colin's
    # fire and act as a motivator to him.
    # On another note, Colin's  high  fives per 36  have
    # been  through  the roof recently. It  really seems
    # like  something he's been focusing on in  practice
    # lately,  as well  as putting extra reps in at  the
    # gym.
    # Keep   an   eye   out   for  Colin,  could  be  an
    # interesting 10 day pickup down the line.